Process and apparatus for distributing hydrocarbon feed to a catalyst stream

ABSTRACT

A process and apparatus described is for distributing hydrocarbon feed to catalyst in a riser. Hydrocarbon feed is delivered to a plenum in the riser. Nozzles from the plenum inject feed into the riser to contact the catalyst. Streams of regenerated catalyst and carbonized catalyst may be passed to the riser and mixed around an insert in a lower section of a riser. The plenum may be located in the riser.

BACKGROUND OF THE INVENTION

The invention relates to a process and apparatus for distributinghydrocarbon feed to be contacted with catalyst. A field of the inventionmay be the field of fluid catalytic cracking (FCC).

FCC is a hydrocarbon conversion process accomplished by contactinghydrocarbons in a fluidized reaction zone with a catalyst composed offinely divided particulate material. The reaction in catalytic cracking,as opposed to hydrocracking, is carried out in the absence ofsubstantial added hydrogen or the consumption of hydrogen. As thecracking reaction proceeds substantial amounts of highly carbonaceousmaterial referred to as coke are deposited on the catalyst to providecoked or carbonized catalyst. This carbonized catalyst is often referredto as spent catalyst. However, this term may be misconstrued because thecarbonized catalyst still has significant catalytic activity. Vaporousproducts are separated from carbonized catalyst in a reactor vessel.Carbonized catalyst may be subjected to stripping over an inert gas suchas steam to strip entrained hydrocarbonaceous gases from the carbonizedcatalyst. A high temperature regeneration with oxygen within aregeneration zone operation burns coke from the carbonized catalystwhich may have been stripped.

Although the carbonized catalyst carries coke deposits it may still haveactivity. U.S. Pat. No. 3,888,762 discloses mixing carbonized andregenerated catalyst for contact with the hydrocarbon feed. Theregenerated catalyst may be in the range of 593° to 760° C. (1100° to1400° F.) and the carbonized catalyst may be in the range of 482° to621° C. (900° to 1150° F.). U.S. Pat. No. 5,597,537 discloses mixing thecarbonized and regenerated catalyst in a blending vessel to allow theregenerated and carbonized catalyst to reach a temperature equilibriumbefore contacting the hydrocarbon feed. U.S. Pat. No. 7,935,314 B2discloses baffles in the riser to obstruct upward catalyst flow tofoster mixing. A mixed catalyst with more uniform temperature avoidsundesirable hot spots that can generate nonselective cracking to reducethe value of the product hydrocarbons.

FCC can create a variety of products from heavier hydrocarbons. Often, afeed of heavier hydrocarbons, such as a vacuum gas oil, is provided toan FCC reactor. Various products may be produced, including a gasolineproduct and/or light olefins, such as at least one of propylene andethylene. To produce more light olefins, product cuts from FCC effluent,such as naphtha, may be recycled to the riser reactor or to anadditional riser reactor for additional catalytic cracking. Theseproduct cuts may be fed to the riser in a gaseous phase.

Current known methods of distributing a vapor stream to a riser are posetechnical challenges. Typically, distribution would be accomplished byusing a conventional feed distributor but due to the feed stream beingin the vapor phase this would require a significant number ofdistributors to achieve sufficient mass distribution to the riser. Otherknown means of distributing the vapor stream, such as open pipes orpipes with slots at the end, are inefficient at evenly distributing therecycle stream in the riser.

It may be desirable to provide a distributor for distributinghydrocarbon feed to an FCC reactor.

It may be desirable to provide a distributor for distributing gaseoushydrocarbon feed to an FCC reactor.

It may also be desirable to provide a distributor for distributinghydrocarbon feed to an FCC reactor that assists with mixing of separatestreams of catalyst.

SUMMARY OF THE INVENTION

This invention relates generally to an improved FCC process andapparatus. Specifically, this invention may relate to an improved feeddistributor and may be useful for FCC operation to spray vaporized feedinto a reactor riser.

In a process embodiment, the present invention is a fluid catalyticprocess comprising feeding a stream of catalyst to a riser. A vaporoushydrocarbon feed stream is fed to a plenum in the riser. The hydrocarbonfeed stream from the plenum is injected away from a radial center of theriser into the riser. Lastly, the hydrocarbon feed stream and the streamof catalyst are passed up the riser.

In an additional process embodiment, the present invention is a fluidcatalytic process comprising feeding a first stream of catalyst and asecond stream of catalyst to a riser. A hydrocarbon feed stream is fedto a plenum in the riser. The hydrocarbon feed is injected from theplenum into the riser. The hydrocarbon feed stream is contacted with thefirst stream of catalyst and the second stream of catalyst. Lastly, thehydrocarbon feed stream, the first stream of catalyst and the secondstream of catalyst are passed up the riser.

In a further process embodiment, the present invention is a process fordistributing feed to a riser comprising feeding a first stream ofcatalyst and a second stream of catalyst to the riser. A hydrocarbonfeed stream is fed to a plenum in the riser. The first stream ofcatalyst is passed around an insert comprising the plenum to mix withthe second stream of catalyst and the second stream of catalyst ispassed around the insert to mix with the first stream of catalyst toprovide a mixed stream of catalyst. The hydrocarbon feed stream isinjected from the plenum into the riser. The hydrocarbon feed stream iscontacted with the mixed stream of catalyst and the hydrocarbon feedstream and the mixed stream of catalyst are passed up the riser.

In an apparatus embodiment, the present invention is an apparatus forfluid catalysis comprising a riser. A plenum is located in a radialcenter of the riser. Lastly, a nozzle in the plenum has an outlet enddirected away from the radial center for injecting hydrocarbon feed.

In an additional apparatus embodiment, the present invention is anapparatus for fluid catalysis comprising a riser. An insert in the riserdefines a space between a wall of the riser and a wall of the insert. Anozzle in the insert is for injecting hydrocarbon feed. A first catalystinlet is in communication with the riser and a second catalyst inlet isin communication with the riser. The insert in the riser is between thefirst catalyst inlet and the second catalyst inlet.

In a further apparatus embodiment, the present invention is an apparatusfor fluid catalysis comprising a riser. An insert in the riser defines aspace between a wall of the riser and a wall of the insert. A nozzle inthe insert is for injecting hydrocarbon feed. A first catalyst inlet isin communication with the riser, and a second catalyst inlet is incommunication with the riser. The insert in the riser is between thefirst catalyst inlet and the second catalyst inlet, and the nozzle isdisposed at a higher elevation than the first catalyst inlet and thesecond catalyst inlet.

The feed distributor evenly distributes the hydrocarbon stream which maybe a vapor stream to the riser. The feed stream may be distributedutilizing numerous nozzles located in a lower section of the riser. Adual diameter nozzle may provide a means to independently set the jetoutlet velocity and the distributor pressure drop. The distributor mayalso assist the thorough mixing of streams of catalyst at differenttemperatures to have a more homogeneous temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, elevational view of an FCC unit incorporating thepresent invention.

FIG. 2 is a sectional view of FIG. 1 taken at segment 2-2.

FIG. 3 is an enlarged, partial elevational view of a portion of FIG. 1.

FIG. 4 is a partial, sectional view which is an alternative to FIG. 2.

FIG. 5 is an enlarged, partial elevational view of an alternativeembodiment to FIG. 3.

FIG. 6 is a partial, elevation view of an alternative to FIG. 1

FIG. 7 is a sectional view taken at segment 7-7 of FIG. 6.

FIG. 8 shows an alternative partial, elevational view to FIG. 6.

DEFINITIONS

The term “communication” means that material flow is operativelypermitted between enumerated components.

The term “downstream communication” means that at least a portion ofmaterial flowing to the subject in downstream communication mayoperatively flow from the object with which it communicates.

The term “upstream communication” means that at least a portion of thematerial flowing from the subject in upstream communication mayoperatively flow to the object with which it communicates.

The term “direct communication” means that flow from the upstreamcomponent enters the downstream component without passing through anintermediate vessel.

The term “feeding” means that the feed passes from a conduit or vesseldirectly to an object without passing through an intermediate vessel.

The term “passing” includes “feeding” and means that the material passesfrom a conduit or vessel to an object.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus and process of the present invention is a distributor fordistributing a hydrocarbon feed to a riser to be contacted withcatalyst. In an aspect, the hydrocarbon feed is in vapor phase. Thedistributor may distribute the only hydrocarbon feed to the riser or anadditional feed to the riser. If the distributor distributes additionalfeed, the feed may be a recycled feed derived from riser effluent.Accordingly, the hydrocarbon feed may be a conventional FCC feed or alight hydrocarbon stream. The distributor may distribute feed to a lowerend of a riser in which regenerated catalyst and carbonized catalyst aremixed for contact with the hydrocarbon feed. The present invention maybe useful in any solids-gas contacting equipment. However, readyusefulness is found in an FCC unit.

FIG. 1 shows an FCC unit 8 that includes a reactor vessel 20 and aregenerator vessel 50. A first regenerated catalyst conduit 12 transfersa first regenerated catalyst stream from the regenerator vessel 50 at arate regulated by a control valve 14 through a regenerated catalystinlet 15 of the first regenerated catalyst conduit 12 to the reactorriser 10. The first regenerated catalyst inlet 15 is in upstreamcommunication with the riser 10. An optional second carbonized catalystconduit 52 transfers a second carbonized catalyst stream from thereactor vessel 20 at a rate regulated by a control valve 53 through acarbonized catalyst inlet 97 of the second carbonized catalyst conduit52 to the reactor riser 10. The optional second carbonized catalystinlet 97 is in upstream communication with the riser 10.

The riser 10 is an elongated vertical tube typically made of killedcarbon steel. The riser 10 may comprise a lower section 11 and an uppersection 17. The upper section 17 may be made of chrome steel. The lowersection 11 may include a hemispherical bottom. The lower section 11 mayhave a larger inner diameter than the upper section 17 of the riser. Theenlarged lower section 11 may include a frustoconical or curvedtransition section 13 that tapers between the enlarged diameter of theenlarged lower section and the narrowed diameter of a narrowed uppersection 17 of the riser. If the hydrocarbon feed to the lower end 11 ofthe riser 10 is vaporous, the transition section 13 is less necessary ormay be omitted. The first regenerated catalyst conduit 12 and the secondoptional carbonized catalyst conduit 52 may connect to the lower section11 at a wall 90 of the lower section at inlets 15 and 97, respectively.The inner surface of the entire riser 10 may be coated with a refractorymaterial.

A fluidization medium such as steam from a distributor 19 in the lowersection 11 urges catalyst upwardly through the riser 10 at a relativelyhigh density. An optional plurality of feed distributors 18 located inthe upper section 17 of the riser 10 just above the optional transitionsection 13 inject a primary hydrocarbon feed across the flowing streamof catalyst particles to distribute hydrocarbon feed to the riser 10.The only hydrocarbon feed or a secondary hydrocarbon feed derived fromcracking the primary feed may be fed to the riser 10 in the lowersection 11. Upon contacting the hydrocarbon feed with catalyst in thereactor riser 10 the heavier hydrocarbon feed cracks to produce lightergaseous hydrocarbon product while coke is deposited on the catalystparticles to produce carbonized catalyst.

A conventional FCC feedstock and higher boiling hydrocarbon feedstockare suitable primary hydrocarbon feeds. The most common of suchconventional feedstocks is a “vacuum gas oil” (VGO), which is typicallya hydrocarbon material having a boiling range of from 343° to 552° C.(650 to 1025° F.) prepared by vacuum fractionation of atmosphericresidue. Such a fraction is generally low in coke precursors and heavymetal contamination which can serve to contaminate catalyst. Heavyhydrocarbon feedstocks to which this invention may be applied includeheavy bottoms from crude oil, heavy bitumen crude oil, shale oil, tarsand extract, deasphalted residue, products from coal liquefaction,atmospheric and vacuum reduced crudes. Heavy feedstocks for thisinvention may also include mixtures of the above hydrocarbons and theforegoing list is not comprehensive.

It is also contemplated that lighter recycle or previously cracked feedssuch as naphtha may be a suitable secondary or the only hydrocarbonfeedstock to the riser. A light naphtha fraction suitable as the onlyfeed or a secondary feed to the riser may have an initial boiling point(IBP) below about 127° C. (260° F.) in the C₅ range; i.e., about 35° C.(95° F.), and an end point (EP) at a temperature greater than or equalto about 127° C. (260° F.). The boiling points for these fractions aredetermined using the procedure known as ASTM D86-82. A heavy naphthafraction suitable as the only feed or a secondary feed to the riser mayhave an IBP at or above about 127° C. (260° F.) and an EP at atemperature above about 200° C. (392° F.), preferably between about 204°and about 221° C. (400° and 430° F.). A full range naphtha fractionsuitable as the only feed or a secondary feed to the riser may have aninitial boiling point (IBP) below about 127° C. (260° F.) in the C₅range; i.e., about 35° C. (95° F.) and an EP at a temperature aboveabout 200° C. (392° F.), preferably between about 204° and about 221° C.(400° and 430° F.).

The reactor vessel 20 is in downstream communication with the riser 10.In the reactor vessel, the carbonized catalyst and the gaseous productare separated. The resulting mixture of gaseous product hydrocarbons andcarbonized catalyst continues upwardly through the riser 10 into thereactor vessel 20 in which the carbonized catalyst and gaseous productare separated. A pair of disengaging arms 22 may tangentially andhorizontally discharge the mixture of gas and catalyst from a top of theriser 10 through one or more outlet ports 24 (only one is shown) into adisengaging vessel 26 to effect partial separation of gases from thecatalyst. Two, three or four disengaging arms 22 may be used dependingon the size of the FCC unit 8.

A transport conduit 28 carries the hydrocarbon vapors, includingstripped hydrocarbons, stripping media and entrained catalyst to one ormore cyclones 30 in the reactor vessel 20 which separates carbonizedcatalyst from the product hydrocarbon gaseous stream. The disengagingvessel 26 is partially disposed in the reactor vessel 20 and can beconsidered part of the reactor vessel 20. A collection plenum 34 in thereactor vessel 20 gathers the separated hydrocarbon gaseous streams fromthe cyclones 30 for passage to an outlet nozzle 36 and eventually into afractionation recovery zone (not shown). Diplegs 38 discharge catalystfrom the cyclones 30 into a lower bed 29 in the reactor vessel 20. Thecatalyst with adsorbed or entrained hydrocarbons may eventually passfrom the lower bed 29 into an optional stripping section 40 across ports42 defined in a wall of the disengaging vessel 26. Catalyst separated inthe disengaging vessel 26 may pass directly into the optional strippingsection 40 via the bed 29. A fluidizing conduit 45 delivers inertfluidizing gas, typically steam, to the stripping section 40 through afluidizing distributor 46.

The stripping section 40 contains baffles 43, 44 or other equipment topromote contacting between a stripping gas and the catalyst. Thestripped, carbonized catalyst leaves the stripping section 40 of thedisengaging vessel 26 of the reactor vessel 20 with a lowerconcentration of entrained or adsorbed hydrocarbons than it had when itentered or if it had not been subjected to stripping. A first portion orall of the carbonized catalyst leaves the disengaging vessel 26 of thereactor vessel 20 through a spent catalyst conduit 48 and feeds into theregenerator vessel 50 at a rate regulated by a control valve 51. Anoptional second portion of the carbonized catalyst that has been cokedin the reactor riser 10 leaves the disengaging vessel 26 of the reactorvessel 20 and is fed through the second carbonized catalyst conduit 52back to the riser 10 at a rate regulated by a control valve 53. Theoptional second carbonized catalyst conduit 52 is in downstreamcommunication with the reactor vessel 20. The second carbonized catalystconduit 52 is in downstream communication with the outlet port 24 of theriser 10 and in upstream communication with a carbonized catalyst inlet97 of the second carbonized catalyst conduit 52 to the riser 10.

The riser 10 of the FCC process is maintained at high temperatureconditions which generally include a temperature above about 425° C.(797° F.). In an embodiment, the reaction zone is maintained at crackingconditions which include a temperature of from about 480° to about 621°C. (896° to 1150° F.) at the riser outlet port 24 and a pressure fromabout 69 to about 517 kPa (ga) (10 to 75 psig) but typically less thanabout 275 kPa (ga) (40 psig). The catalyst-to-oil ratio, based on theweight of catalyst and feed hydrocarbons entering the bottom of theriser, may range up to 30:1 but is typically between about 4:1 and about10:1 and may range between 7:1 and 25:1. Hydrogen is not normally addedto the riser, although hydrogen addition is known in the art. Steam maybe passed into the riser 10 and reactor vessel 20 equivalent to about2-35 wt-% of feed. Typically, however, the steam rate will be betweenabout 2 and about 7 wt-% for maximum gasoline production and about 10 toabout 20 wt-% for maximum light olefin production. The average residencetime of catalyst in the riser may be less than about 5 seconds. The typeof catalyst employed in the process may be chosen from a variety ofcommercially available catalysts. A catalyst comprising a zeoliticmaterial such as Y zeolite is preferred, but the older style amorphouscatalysts can be used if desired. Additionally, shape-selectiveadditives such as ZSM-5 may be included in the catalyst composition toincrease light olefin production.

The regenerator vessel 50 is in downstream communication with thereactor vessel 20. In the regenerator vessel 50, coke is combusted fromthe portion of carbonized catalyst delivered to the regenerator vessel50 by contact with an oxygen-containing gas such as air to provideregenerated catalyst. The regenerator vessel 50 may be a combustor typeof regenerator, which may use hybrid turbulent bed-fast fluidizedconditions in a high-efficiency regenerator vessel 50 for completelyregenerating carbonized catalyst. However, other regenerator vessels andother flow conditions may be suitable for the present invention. Thespent catalyst conduit 48 feeds carbonized catalyst to a first or lowerchamber 54 defined by outer wall 56 through a spent catalyst inlet chute62. The carbonized catalyst from the reactor vessel 20 usually containscarbon in an amount of from 0.2 to 2 wt-%, which is present in the formof coke. Although coke is primarily composed of carbon, it may containfrom 3 to 12 wt-% hydrogen as well as sulfur and other materials. Anoxygen-containing combustion gas, typically air, enters the lowerchamber 54 of the regenerator vessel 50 through a conduit 64 and isdistributed by a distributor 66. As the combustion gas enters the lowerchamber 54, it contacts carbonized catalyst entering from chute 62 andlifts the catalyst at a superficial velocity of combustion gas in thelower chamber 54 of perhaps at least 1.1 m/s (3.5 ft/s). In anembodiment, the lower chamber 54 may have a catalyst density of from 48to 320 kg/m³ (3 to 201b/ft³) and a superficial gas velocity of 1.1 to6.1 m/s (3.5 to 10 ft/s). The oxygen in the combustion gas contacts thecarbonized catalyst and combusts carbonaceous deposits from the catalystto at least partially regenerate the catalyst and generate flue gas.

In an embodiment, to accelerate combustion of the coke in the lowerchamber 54, hot regenerated catalyst from a dense catalyst bed 59 in anupper or second chamber 70 may be recirculated into the lower chamber 54via an external recycle catalyst conduit 67 regulated by a control valve69. Hot regenerated catalyst enters the lower chamber 54 through aninlet chute 63. Recirculation of regenerated catalyst, by mixing hotcatalyst from the dense catalyst bed 59 with relatively coolercarbonized catalyst from the spent catalyst conduit 48 entering thelower chamber 54, raises the overall temperature of the catalyst and gasmixture in the lower chamber 54.

The mixture of catalyst and combustion gas in the lower chamber 54ascend through a frustoconical transition section 57 to the transport,riser section 60 of the lower chamber 54. The riser section 60 defines atube which is preferably cylindrical and extends preferably upwardlyfrom the lower chamber 54. The mixture of catalyst and gas travels at ahigher superficial gas velocity than in the lower chamber 54. Theincreased gas velocity is due to the reduced cross-sectional area of theriser section 60 relative to the cross-sectional area of the lowerchamber 54 below the transition section 57. Hence, the superficial gasvelocity may usually exceed about 2.2 m/s (7 ft/s). The riser section 60may have a lower catalyst density of less than about 80 kg/m³ (5lb/ft³).

The regenerator vessel 50 also includes an upper or second chamber 70.The mixture of catalyst particles and flue gas is discharged from anupper portion of the riser section 60 into the upper chamber 70.Substantially completely regenerated catalyst may exit the top of thetransport, riser section 60, but arrangements in which partiallyregenerated catalyst exits from the lower chamber 54 are alsocontemplated. Discharge is effected through a disengaging device 72 thatseparates a majority of the regenerated catalyst from the flue gas. Inan embodiment, catalyst and gas flowing up the riser section 60 impact atop elliptical cap 65 of the riser section 60 and reverse flow. Thecatalyst and gas then exit through downwardly directed discharge outlets73 of disengaging device 72. The sudden loss of momentum and downwardflow reversal cause a majority of the heavier catalyst to fall to thedense catalyst bed 59 and the lighter flue gas and a minor portion ofthe catalyst still entrained therein to ascend upwardly in the upperchamber 70. Cyclones 82, 84 further separate catalyst from ascending gasand deposits catalyst through dip legs 85, 86 into dense catalyst bed59. Flue gas exits the cyclones 82, 84 and collects in a plenum 88 forpassage to an outlet nozzle 89 of regenerator vessel 50 and perhaps intoa flue gas or power recovery system (not shown). Catalyst densities inthe dense catalyst bed 59 are typically kept within a range of fromabout 640 to about 960 kg/m³ (40 to 601b/ft³). A fluidizing conduit 74delivers fluidizing gas, typically air, to the dense catalyst bed 59through a fluidizing distributor 76. In a combustor-style regenerator,approximately no more than 2% of the total gas requirements within theprocess enter the dense catalyst bed 59 through the fluidizingdistributor 76. In this embodiment, gas is added here not for combustionpurposes but only for fluidizing purposes, so the catalyst will fluidlyexit through the catalyst conduits 67 and 12. The fluidizing gas addedthrough the fluidizing distributor 76 may be combustion gas. In the casewhere partial combustion is effected in the lower chamber 54, greateramounts of combustion gas will be fed to the upper chamber 70 throughfluidizing conduit 74.

From about 10 to 30 wt-% of the catalyst discharged from the lowerchamber 54 is present in the gases above the outlets 73 from the risersection 60 and enter the cyclones 82, 84. The regenerator vessel 50 maytypically require 14 kg of air per kg of coke removed to obtain completeregeneration. When more catalyst is regenerated, greater amounts of feedmay be processed in a conventional reactor riser. The regenerator vessel50 typically has a temperature of about 594 to about 732° C. (1100 to1350° F.) in the lower chamber 54 and about 649 to about 760° C. (1200to 1400° F.) in the upper chamber 70. The regenerated catalyst conduit12 is in downstream communication with the regenerator vessel 50 andcommunicates with the riser 10. Regenerated catalyst from dense catalystbed 59 is transported through regenerated catalyst conduit 12 as a firststream of catalyst from the regenerator vessel 50 back to the reactorriser 10 through the control valve 14 where it again contacts feed asthe FCC process continues. Carbonized catalyst in the optional secondcatalyst conduit 52 comprises a second stream of catalyst.

In an embodiment shown in FIG. 1 which utilizes two catalyst conduitsand two catalyst streams, the first regenerated catalyst conduit 12 andthe second carbonized catalyst conduit 52 connect to and are incommunication with the riser 10. The first stream of regeneratedcatalyst in the first regenerated catalyst conduit 12 and the secondstream of carbonized catalyst in the second carbonized catalyst conduit52 are fed to the riser 10 and mixed together. One or both of the firstregenerated catalyst conduit 12 and the second carbonized catalystconduit 52 may tangentially connect to the lower section 11 of the riser10 tangentially to impart an angular motion to catalyst discharged intothe riser to promote mixing therein. Additionally, ramps may beinstalled at the connection between one or both of the first regeneratedcatalyst conduit 12 and the second carbonized catalyst conduit 52 andthe lower section 11 of the riser 10 also to promote mixing in the lowersection 11.

The riser may include an insert 92. In an aspect, the lower section 11of the riser 10 may include the insert 92. In an aspect, the insert 92is contained in the lower section 11 of the riser. The insert 92 mayhave an outer wall 94 that may be spaced apart from an inner surface ofthe wall 90 of the lower section 11 of the riser 10. In an aspect, theinsert 92 is radially centered in the lower section 11 of the riser 10.In other words, although not shown, the insert 92 has a centrallongitudinal axis aligned with a central longitudinal axis of the riser10. In a further aspect, the outer wall 94 of the insert is a verticalwall. The inner diameter D_(I) of the insert 92 may be between 0.6 and1.5 and preferably between 0.8 and 1.2 times the inner diameter D_(C) ofthe largest one of the first regenerated catalyst conduit 12 and thesecond carbonized catalyst conduit 52.

The wall 94 of the insert 92 and the wall 90 of the riser define a space96 therebetween. In an aspect, insert 92 and the lower section 11 mayeach be tubular so that together they define an annular space 96 orannulus between the wall 94 of the insert 92 and the wall 90 of thelower section 11. The first regenerated catalyst conduit 12 and thesecond carbonized catalyst conduit 52 may communicate with the space 96,so the first regenerated catalyst conduit 12 feeds the first stream ofregenerated catalyst to the space 96 and the second carbonized catalystconduit 52 feeds the second stream of carbonized catalyst to the space96. The catalyst in the space 96 is fluidized by fluidizing gas, such assteam, from fluidizing distributor 19. The first stream of regeneratedcatalyst from the first catalyst inlet 15 passes around the insert 92 tomix with the second stream of carbonized catalyst from the secondcatalyst inlet 97 and the second stream of catalyst from the secondcatalyst inlet 97 passes around the insert 92 to mix with the firststream of catalyst from the first catalyst inlet 15. The mixed stream ofthe first stream of catalyst and the second stream of catalyst then passup the riser.

In an aspect, the wall 94 of the insert 92 may be impermeable tocatalyst, so it prevents catalyst from passing into the insert. Theinsert 92 has a closed top which may comprise a hemispherical head whichmay also be impermeable to catalyst, so it prevents catalyst fromentering into the top of the insert 92. Accordingly, the entire insert92 may be impermeable to catalyst, so no catalyst enters into the insert92.

The insert may be located in a lower section 11 of the riser 10. Theupper section 17 of the riser 10 may be above the insert 92. In anaspect, the frustoconical transition section 13 of the riser which maybe between an enlarged section 11 and a narrowed upper section 17 totransition the larger diameter of the enlarged lower section 11 to thenarrowed upper section 17 may transition a mixed stream of the firststream of regenerated catalyst and the second stream of carbonizedcatalyst from the enlarged lower section to the narrowed upper sectionas the mixed stream of catalyst is passed up the riser. In an aspect,the insert 92 does not extend into the transition section 13, so thetransitioning occurs after the mixed stream of catalyst is passed abovethe insert 92.

The insert 92 may comprise a plenum 98 to which hydrocarbon feed issupplied. In an aspect, the hydrocarbon feed is a vaporous hydrocarbonfeed. In an aspect, the hydrocarbon feed supplied to the plenum 98 maybe the only hydrocarbon feed fed to the riser 10 or it may be asecondary feed fed in addition to a primary feed fed to the riser. Theplenum 98 may be located in a radial center of the riser in the insert92. The insert 92 may be hollow and the plenum 98 may occupy all or aportion of an interior cavity defined by the outer wall 94 and top ofthe insert. A nozzle 102 in the plenum may inject hydrocarbon feed fromthe plenum 98 into the riser. In an aspect, the nozzle 102 may injecthydrocarbon feed into the space 96 between the insert 92 and the wall 90of the riser 10. In a further aspect, the nozzle 102 injects thehydrocarbon feed stream from the 98 plenum away from a radial center ofthe riser into the riser. In a further aspect, a plurality of nozzles102 in the plenum arrayed around the perimeter of the plenum all injecthydrocarbon feed from the plenum 98 into the riser. In a further aspectthe hydrocarbon feed injected from the nozzles 102 is in gaseous phasewhile it is in the plenum 98 before being sprayed into the riser 98. Themixed stream of catalyst contacts the injected hydrocarbon feed streamand the mixed stream of catalyst and hydrocarbon feed pass up the riser.In an aspect, the lowest nozzle 102 is about 1 to about 3 riser innerdiameters D_(r) above a top of the highest catalyst inlet 15.

In an aspect, primary feed distributors 18 may be disposed in the uppersection 17 of the riser 10 above the lower section 11, the transitionsection 13 and the insert 92. Consequently, the primary feed may beinjected into the ascending mixed stream of catalyst and hydrocarbonfeed.

It is anticipated that the insert 92 be made of stainless steel such as300 Series stainless steel and be lined with refractory. Additionally,the insert 92 may be made of or coated with a ceramic or other materialthat resists erosion.

FIG. 2 shows a plan sectional view of segment 2-2 taken in FIG. 1.Refractory lining 104 on the wall 94 of the insert 92 and the walls ofthe lower section 11 of the riser 10, the first regenerated catalystconduit 12 and the second carbonized catalyst conduit 52 are shown inFIG. 2, but not in FIG. 1. The insert 92 may be located in the lowersection 11 of the riser 10. The first catalyst conduit 12 is connectedto the riser 10 at a first catalyst inlet 15 and the second catalystconduit 52 is connected to the riser 10 at a second catalyst inlet 97,and the insert 92 is interposed between the first catalyst inlet and thesecond catalyst inlet. In an aspect, the first catalyst conduit 12 maybe connected to the riser 10 at a first catalyst inlet 15 located in thesection 11 of the riser 10, the second catalyst conduit 52 may beconnected to the riser 10 at a second catalyst inlet 97 located in thelower section 11 of the riser 10. The first stream of catalyst and thesecond stream of catalyst may be fed to the space 96 between the wall 90of the riser and the wall 94 of the insert 92.

The first stream of regenerated catalyst is passed from the firstregenerated catalyst inlet 15 around the wall 94 of the insert 92 in theriser 10 to mix with the second stream of carbonized catalyst from thesecond carbonized catalyst inlet 97, and the second stream of carbonizedcatalyst is passed from the second carbonized catalyst inlet 97 aroundthe wall 94 of the insert 92 in the riser 10 to mix with the firststream of regenerated catalyst from the first regenerated catalyst inlet15. The first stream of catalyst and the second stream of catalyst maypass around the annular space 96 in the riser 10 to mix with each other.The mixed stream of the first stream of regenerated catalyst and thesecond stream of carbonized catalyst may pass around the insert 92 andup the riser 10.

The nozzles 102 may have an outlet ends 106 directed away from saidradial center C of the riser for injecting hydrocarbon feed into theriser to contact the mixed stream of catalyst rising from the catalystinlets 15 and 97 propelled by fluidizing gas from distributor 19 (FIG.1, not shown in FIG. 2 for simplicity). Nozzles 102 may be disposed at ahigher elevation than the first catalyst inlet 15 and the secondcatalyst inlet 97, so the feed is injected into a thoroughly mixedstream of the first catalyst stream and the second catalyst stream.

FIG. 3 is an enlarged, partial elevational view of the top of the insert92 and plenum 98 of FIG. 1. The profile of the nozzles 102 are shown forillustrative purposes in FIG. 3. Each nozzle 102 has an inlet end 108 inthe plenum 98 and an outlet end 106 at the outlet wall 94 of the insert92. The hydrocarbon feed is injected from a plurality of nozzles 102with an inlet end 108 inside of the plenum 98. The inlet end 108 has anopening 114 therein having an inner diameter D_(i). The outlet end 106has an opening 116, shown in dashed lines, therein having an innerdiameter D_(o). The hydrocarbon stream is distributed through numerousdual diameter nozzles 102 located in the riser. The dual diameter nozzle102 provides a means to independently set the jet outlet velocity andthe distributor pressure drop of vaporous hydrocarbon feed. The jetoutlet velocity is adjusted by the number and area of the openings 116in the outlet ends 106 of the nozzles 102 while the pressure drop is setby the number and area of the openings 114 in the inlet end 108 in theplenum 98. The nozzles 102 typically will have inner diameters D_(i) inthe opening 114 in the inlet end 108 that are smaller than the innerdiameters D_(o) of the opening 116 in the outlet end 106 of the nozzle102.

FIG. 4 shows an alternative enlarged partial plan view of FIG. 2.Elements in FIG. 4 with the same configuration as in FIG. 2 will havethe same reference numeral as in FIG. 2. Elements in FIG. 4 which have adifferent configuration as the corresponding element in FIG. 2 will havethe same reference numeral but be succeeded with a prime symbol (′). Theapparatus and process in FIG. 4 is the same as in FIG. 2 with theexception of the noted following differences. In FIG. 4, the nozzles102′ are disposed tangentially with respect to a outer wall of theplenum 98′ which is the outer wall 94′ of the insert 92′. The outer wall94′ to which the nozzles 102′ are tangential may be a vertical wall. Thenozzles 102′ have the same configuration as in FIG. 2, but are orientedtangentially to promote feed and catalyst mixing. The nozzles 102′inject hydrocarbon feed tangentially from the plenum 98′. The outletends 106′ of the nozzles are directed away from a radial center of saidriser. The outer wall 94′ of the insert 92′ may be coated withrefractory 104, so the tangentialness of the nozzles 102′ may be relatedto the coating of refractory 104.

FIG. 5 shows an alternative view of FIG. 3. Elements in FIG. 5 with thesame configuration as in FIG. 3 will have the same reference numeral asin FIG. 3. Elements in FIG. 5 which have a different configuration asthe corresponding element in FIG. 3 will have the same reference numeralbut be succeeded with a double prime symbol (″). The apparatus andprocess in FIG. 5 is the same as in FIG. 3 with the exception of thenoted following differences. In FIG. 5, the insert 92″ has a dished top118 with nozzles 102″ directed radially upwardly from the plenum 98″through the dished top 118. The nozzles 102″ inject the hydrocarbon feedupwardly from said plenum 98″. The nozzles 102″ may have the sameconfiguration as in FIG. 3, but are oriented radially to promote feedand catalyst mixing and upward fluidization. The nozzles 102″ inject thehydrocarbon feed stream through a top of the plenum 98″.

FIG. 6 is an enlarged sectional view of an alternative embodiment toFIG. 1 of a lower section 211 of a riser 210. Elements in FIG. 6 withthe same configuration as in FIG. 1 will have the same reference numeralas in FIG. 1. Elements in FIG. 6 which have a different configuration asthe corresponding element in FIG. 1 will have the same reference numeralbut be preceded with a numeral “2”. The apparatus and process in FIG. 6is the same as in FIG. 1 with the exception of the noted followingdifferences.

In FIG. 6, an insert 292 includes at least one opening 120 to a chamber122 inside the insert. A plenum 298 is disposed in the insert 292. In anaspect, the plenum 298 is disposed in a top of the insert 292. A baffle124 isolates the chamber 122 from the plenum 298 in the interior of theinsert 292. A conduit 126 extends from outside of the riser 210 throughthe chamber 122 to the plenum 298 for passing hydrocarbon feed to theplenum. The conduit 126 may extend through a bottom of the riser 210. Atleast one nozzle 202, and in an aspect, a plurality of nozzles 202,injects hydrocarbon feed from the plenum 298 into the riser 210. Outletends 206 of the nozzles 202 are disposed in the riser 210. In an aspect,the nozzles 202 inject hydrocarbon feed into a lower section 211 of theriser 210.

The chamber 122 may include at least one opening 120 in the wall 294located in a space 296 between the wall 294 of the insert 292 and a wall290 of the riser 210. The opening 120 may be spaced apart from the wall290 of the riser 210. The opening 120 may serve as an entrance to aninterior of the chamber 122. The chamber 122 may be in communicationwith the first regenerated catalyst conduit 212 and the secondcarbonized catalyst conduit 252, so at least a portion of the firststream of regenerated catalyst and at least a portion of the secondstream of carbonized catalyst may pass from the space 296 into thechamber 122 through the opening 120 in the chamber. In an aspect, anupper most portion of the opening 120 may be at an elevation above alower most portion, and preferably an upper most portion, of a secondcatalyst inlet 297. In a further aspect, an upper most portion of theopening 120 may be at an elevation above a lower most, and preferably anupper most portion, of a first catalyst inlet 215. Hence, the firststream of regenerated catalyst may pass from the inlet 215 of the firstcatalyst conduit 212, and the second stream of carbonized catalyst maypass from the inlet 297 of the second catalyst conduit 252 may pass atleast partially upwardly through the opening 120 into the chamber 122through the space 296 between the wall 290 of the riser 210 and the wall294 of the insert 292. One or a plurality of openings 120 a and 120 bmay be provided in the wall 294. At least one opening 120 may have anelongated configuration that is spaced from the top of the insert 292.

FIG. 7 shows a plan sectional view of segment 7-7 taken in FIG. 6.Refractory lining 104 on the wall 294 of the insert 292 and the wall ofthe lower section 211 of the riser 210, the conduit 126, the firstregenerated catalyst conduit 212 and the second carbonized catalystconduit 252 is shown in FIG. 7. The first regenerated catalyst conduit212 and the second carbonized catalyst conduit 252 define a 150 degreeangle instead of a 180 degree angle as in FIG. 2. The wall 294 of theinsert 292 comprises three arcuate sections 294 a-c that define threeopenings 120 a-c. Two openings 120 a and 120 b may have a smaller widththan a third opening 120 c. In an aspect, the two smaller openings 120 aand 120 b have the same arcuate width. Arcuate section 294 a opposes thenearest catalyst conduit which may be the second carbonized catalystconduit 252 and particularly the second catalyst inlet 297 thereof.Arcuate section 294 b also opposes the nearest catalyst conduit whichmay be the first regenerated catalyst conduit 212 and particularly thefirst catalyst inlet 215 thereof. The third arcuate section 294 c isoptional. Dashed lines show central longitudinal axis A of the firstregenerated catalyst conduit into the riser 10 and central longitudinalaxis B of the second carbonized catalyst conduit 252 into the riser. Theopenings 120 are all not intersected by a longitudinal axis A, B of anearest one of the first regenerated catalyst conduit 212 and the secondcarbonized catalyst conduit 252 into the riser. In other words, thefirst catalyst inlet 215 and the second catalyst inlet 297 are azimuthalto openings 120 a-c. Arcuate sections 294 a and 294 b may be narrower orwider than the closest catalyst inlet 215, 297. Conduit 126 is protectedfrom direct impact by catalyst streams by arcuate sections 294 a and 294b of wall 294. The conduit 126 may be coated in refractory 104 forprotection.

The first stream of regenerated catalyst is passed from the firstregenerated catalyst inlet 215 around the arcuate section 294 b of thewall 294 of the insert 292 in the riser 210 to mix with the secondstream of carbonized catalyst from the second carbonized catalyst inlet297, and the second stream of carbonized catalyst is passed from thesecond carbonized catalyst inlet 297 around the arcuate section 294 a ofthe wall 294 of the insert 292 in the riser 210 to mix with the firststream of regenerated catalyst from the first regenerated catalyst inlet215. Additionally, the first stream of catalyst may pass throughopenings 120 into the chamber 122 in the insert 292 to mix with thesecond stream of catalyst and the second stream of catalyst may passthrough openings 120 into the chamber 122 to mix with first stream ofcatalyst.

In an aspect, the at least one opening 120 in the wall 294 of the insert292 may serve as an exit from the chamber 122. Consequently, the firststream of regenerated catalyst and the second stream of carbonizedcatalyst may pass through the opening 120 from the chamber 122 back intothe space 296. By virtue of the first and second catalyst streamspassing around the insert 292 and entering into and exiting from thechamber 122 through the at least one opening 120 in the wall 294 of theinsert 292, the catalyst streams mix together to provide a mixed streamof catalyst with a more-homogeneous temperature throughout the mixedstream of catalyst.

Turning back to FIG. 6, the mixed stream of the first stream of catalystand the second stream of catalyst passes from the insert 292 in theriser 210 upwardly from the lower section 211 and is contacted with thehydrocarbon feed injected from nozzles 202 in the plenum 298 locatedabove the opening 120 in the riser 210. In an aspect, the lowest nozzle202 a is about 1 to about 3 riser inner diameters D_(r) above a top ofthe highest catalyst inlet 215. In an aspect, the hydrocarbon feed inthe plenum 298 is vaporous.

FIG. 8 shows an alternative elevational partial view of FIG. 6. Elementsin FIG. 8 with the same configuration as in FIG. 6 will have the samereference numeral as in FIG. 6. Elements in FIG. 8 which have adifferent configuration as the corresponding element in FIG. 6 will havethe same reference numeral but be succeeded with a prime symbol (′). Theapparatus and process in FIG. 8 is the same as in FIG. 6 with theexception of the noted following differences. In FIG. 8, outlet ends206′ of the nozzles 202′ are disposed in the chamber 122′. The nozzles202′ are disposed in the plenum 298′ to project hydrocarbon feed intothe chamber 122′. FIG. 8 shows the nozzles 202′ projecting feeddownwardly, but other arrangements or orientations may be suitable. Thenozzles 202′ may have the same configuration as in FIG. 2 but with adifferent orientation as shown in FIG. 8. The nozzles 202′ injecthydrocarbon feed from the plenum 298′ to contact with the first streamof catalyst and the second stream of catalyst in the chamber 122′.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Itshould be understood that the illustrated embodiments are exemplaryonly, and should not be taken as limiting the scope of the invention.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preceding preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

In the foregoing, all temperatures are set forth in degrees Celsius and,all parts and percentages are by weight, unless otherwise indicated.Pressures are given at the vessel outlet and particularly at the vaporoutlet in vessels with multiple outlets.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

1. An apparatus for fluid catalysis comprising: a riser; a plenumlocated in an radial center of said riser; and a nozzle in said plenumwith an outlet end directed away from said radial center for injectinghydrocarbon feed.
 2. The apparatus of claim 1 further comprising aninsert having an outer wall spaced from a wall of said riser and saidplenum is located in said insert.
 3. The apparatus of claim 2 whereinsaid insert includes an opening to a chamber inside said insert.
 4. Theapparatus of claim 1 further comprising: a first catalyst inlet incommunication with the riser; a second catalyst inlet in communicationwith the riser; and said insert in said riser between said firstcatalyst inlet and said second catalyst inlet.
 5. The apparatus of claim4 wherein a first catalyst conduit is connected to said riser at saidfirst catalyst inlet and a second catalyst conduit is connected to saidriser at said second catalyst inlet and the insert is interposed betweensaid first catalyst inlet and said second catalyst inlet.
 6. Theapparatus of claim 1 wherein said insert has dished top with nozzles inthe top.
 7. The apparatus of claim 5 further including a transitionsection of the riser between an enlarged section and a narrowed sectionand the insert does not extend into the transition section.
 8. Theapparatus of claim 5 wherein said nozzle is disposed at a higherelevation than said first catalyst inlet and said second catalyst inlet.9. The apparatus of claim 1 further including a conduit to said plenumfor passing hydrocarbon feed to said plenum.
 10. The apparatus of claim1 wherein said nozzle has an inlet with a smaller inner diameter than anoutlet of said nozzle.
 11. The apparatus of claim 10 wherein said nozzleis disposed tangentially with respect to an outer wall of said plenum.12. The apparatus of claim 10 wherein said nozzle is disposed radiallywith respect to an upper end of said plenum.
 13. An apparatus for fluidcatalysis comprising: a riser; an insert in said riser defining a spacebetween a wall of said riser and a wall of said insert; a nozzle in saidinsert for injecting hydrocarbon feed; a first catalyst inlet incommunication with the riser; a second catalyst inlet in communicationwith the riser; and said insert in said riser between said firstcatalyst inlet and said second catalyst inlet.
 14. The apparatus ofclaim 13 wherein an outlet end of said nozzle is directed away from aradial center of said riser.
 15. The apparatus of claim 13 wherein saidinsert includes an opening to a chamber inside said insert.
 16. Theapparatus of claim 15 wherein an outlet end of said nozzle is disposedin said chamber.
 17. The apparatus of claim 13 wherein said insert has adished top with nozzles in the top.
 18. The apparatus of claim 13wherein said nozzle is disposed at a higher elevation than said firstcatalyst inlet and said second catalyst inlet.
 19. An apparatus forfluid catalysis comprising: a riser; an insert in said defining a spacebetween a wall of said riser and a wall of said insert; a nozzle in saidinsert for injecting hydrocarbon feed; a first catalyst inlet incommunication with the riser; a second catalyst inlet in communicationwith the riser; and said insert in said riser is between said firstcatalyst inlet and said second catalyst inlet and said nozzle isdisposed at a higher elevation than said first catalyst inlet and saidsecond catalyst inlet.
 20. The apparatus of claim 19 wherein a plenum islocated in said insert and said nozzle is in communication with saidplenum.